If you want to make a lot of money, fishing is one great way! There is an island that the dolphin will take you to once you have one heart with it. The fish are worth A LOT more than regular old Dace or Rainbow Trout. If you don't want to make friends with the dolphin, there is an area behind the junk shop that has Salmon that are pretty expensive. Almost everything is better cooked so buy a FULL kitchen. It may be expensive, but it will pay off in the end.